On the Fertilization, Alternation of Generations, and 
General Cytology of the Uredineae 1 . 
BY 
VERNON H. BLACKMAN, M.A., F.L.S., 
Fellow of St. John's College , Cambridge ; Assistant , Department of Botany, British Museum. 
With Plates XXI-XXIV. 
HE question of the sexuality of the Uredineae has been a vexed one 
JL ever since the suggestion put forward by Meyen (34), more than 
sixty years ago, that the spermogonia and aecidia represented the male 
and female organs. This view seemed to receive support from the later 
observations of Tulasne (53), and De Bary (3, 4), who showed that not 
only were spermogonia and aecidia closely associated in a large number of 
forms, but also that the spermatia produced in the spermogonia were 
apparently wanting in any power of germination. It appeared, then, 
possible that the aecidium was the result of the fertilization by a sper- 
matium of a definite female reproductive organ. All workers, however, 
failed either to trace this process or even to produce any evidence of the 
existence of sexual organs at any stage in the development of the aecidium. 
These results, together with the observation that aecidia were sometimes 
produced in the entire absence of spermogonia (see De Bary (4) ; also 
Klebahn (27), p. 194), seemed to negative the view of any actual fertilization 
by the spermatium. 
Owing in part to these observations and to the discovery by Cornu (12), 
in 1875, that the spermatia were capable of germinating to a slight degree in 
nutritive solutions, and also to the later observations of Moller (36) that the 
spermatia of some lichens could develop a mycelium under similar con- 
ditions, Brefeld (10) was led about 1889 to put forward the view that the 
Uredineae (and all the higher Fungi) were without any trace of sexuality 
and that the group should be considered as a family of the Basidiomycetes. 
In his view the spermogonia and spermatia, in this group and in the lichens, 
1 A short preliminary account of the chief results of this work appeared in the New Phytologist, 
vol. iii, 1904, pp. 24-27. 
[Annals of Botany, Vol. XVIII. No. LXXI. July, 1904.] 
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